A torque sensor unit of the type disclosed in Patent Document 1 is conventionally known for use in e.g. a steering device of a vehicle.
A brief explanation of this type of torque sensor unit will be given as follows. Herein, a steering shaft of the steering device has two shaft members relatively rotatably connected to each other through a torsion bar. The torque sensor unit is coupled around one of the shaft members of the steering shaft and includes: a magnetic member having a plurality of magnetic poles arranged in a circumferential direction; a pair of first and second annular yoke members formed of a soft magnetic material with a plurality of radially inwardly extending claw portions and coupled around the other shaft member through a predetermined holder; a pair of first and second magnetosensitive members disposed in a circumferential area between the first and second yoke members so as to face each other (in the axial direction) and adapted to develop a magnetic field between the first and second yoke members; and a magnetic sensor accommodated in an air gap between the first and second magnetosensitive members and adapted to detect a magnetic flux passing through between the magnetosensitive members. By such a structure, the torque sensor unit determines a torque inputted to the steering shaft according to a change in magnetic flux (magnetic flux density) detected by the magnetic sensor.